Effects of pollution by copper and zinc upon some functions of marine and freshwater fish.
A study was undertaken in which both freshwater
and marine fish were chosen as indicator organisms to monitor
pollution by heavy metals (copper and zinc).
Experiments were conducted to determine the adaptability
of guppies to various salt concentrations. Juvenile and
adults guppies were subjected to both abrupt and gradual changes
from freshwater to various salinities. Both could tolerate
gradual transfer from freshwater (S=< 1%, ) to 30%. salinity,
but mortality did occur when they were transferred directly
to different salinities.
Juvenile guppies are more sensitive to copper and
zinc than the adults. The survival rate was found to be increased
with increase in salinity; the LC50 for both adalt and juvenile
guppies increases with increasing salinity. The same results
were found in a marine goby, Pomatoschistus minutus.
The effect of heavy metals were also examined on
the rate of oxygen consumption in both guppies and sticklebacks.
Adding copper to the zinc solution used lowars the rate of
oxygen consumption in sticklebacks but gives a range of values
for the rate of oxygen uptake in guppies. Generally, increasing
the zinc concentration decreases the oxygen consumption in
Plaice and dab were found to accumulate copper and
zinc unevenly in different organs. Liver accumulated the highest concentration of accumulated zinc for both dab and plaice. In
the eight species of fish examined, the liver displayed the
highest concentration of zinc by comparison with the gills